suggestion for your safety bit, you need 3 PIC's running the same sw and
voting on their actions (3 are needed in order to have a majority). You want
independent sensors such that a faulty sensor can be overcome. Isolate the
PIC's from each other. Then you want a 4th PIC running different SW (does
the same job but in a different way)to watchdog the other system. Get
somebody else to write that one and get another person again to check over
it, don't let the 2 dev teams interact on code. Make sure the 4th one is
isolated as much as possible from the other 3. Make it such that any PIC can
sound the alarm that something's wrong. Put voltage and current measurement
on your PIC's and the complete circuits, establish normal operating ranges
for both and have it signal a warning and or an alarm when it goes out of
spec. Make the communication between the PICs happen on individual lines or
via something like CANbus such that if one PIC fails or locks up it wont
lock the bus.

Oh and don't tell microchip about it because I'm pretty sure most of their
products come with a warning about using them in apps where lives are at
stake.

This isn't something that you can take on lightly, and I'd personally
recommend speaking to a professional safe software person. I just cant
remember the keyword but it was developed for air traffic control and NASA
etc for software where lives are at stake.
----- Original Message -----
From: "CVT-SSS" <cvt@CVT-SSS.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, August 11, 2003 1:22 AM
Subject: Re: [PIC:] Baby Incubator Controllers using PICs


> Hi Tom,
>
> That means a Baby Grill Device !!!, I am thinking in safety first. Maybe
two
> controllers working in parallel with a third one checking each others will
> do the work well.  I am planning to use PC100 thermocouples ( there are
very
> sensitive and fast ), heath source must have an external cut off
> sensor/switch to avoid overheath.
> The thing is to send via RS232 any change in temperature, humidity, air
flow
> and maybe the beat rate of the baby4s heart to a remote workstation.
>
> Augusto
>
>
> > No.
> >
> > But I did once work for a company that made "Baby Incubator
Controllers".
> > Fortunately, it was a different division of the company (we made
> > spirometers). The other division had one of their controllers
malfunction
> > and roasted a baby to death.  The bad taste joke was that in the future,
> > they would ship a case of barbeque sauce with each incubator.  If you
are
> > working in this area, always think about failsafe operation.
> >
> > Tom
> >
> > --
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>
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